Gas-oven.



A. H. KOHLMEYER.

GAS OVEN. APPLICATION FILED JAN- 30, 1914.

Patented Apr. '13, 1915.

3 SHEETS-SHBBT 2.

lmwil zizi A. H. KOHLMEYER.

GAS OVEN.

APPLICATION FILED JAN-30, 1914.

Patented Apr. 13, 1915.

3 SHEETSSHEET 3.

AUGUST H. KOI-ILMEYEB, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THERMOAUTOMATIC STOVE COMPANY, OF ST. LOUIS MISSOURI, CORPORATION OF MISSOURI.

Specification of Iietters Patent. v Patented Apr 13, 1915.

Application filed January 30, 1914. Serial No. 815,890.

To all whom it may concern:

Be it known that I, Auoosr H. KOHL- MEYER, a citizen of the UnitedStates, and a resident of the city of St. Louis and State of Missouri,have invented a new and useful.

Improvement in Gas-Ovens, of which the following is a specification.

My invention relates to ovens, particularly to that type in which gas isused for supplying the necessary heat to the oven.

The principal object of my invention is to provide an oven heated by gaswhich will be economical in the use of gas, and which will require theleast amount of attention by the user.

A further object of my inv'ention'is to provide a simple and efficientconstruction having certain other advantages as will appear more fullyhereinafter.

The invention consists in a chamber capable of absorbing and -retaininamount of the heat necessary cooking, and mechanism associated with saidchamber for facilitating the lighting of the gas burners used forheating the chamber, and for automatically cutting off the supply of gasto the burners when the necessary amount of heat has been supplied tosaid chamber. The invention further consists in the parts and thearrangements and combinations of parts, as will be set forthhereinafter.

In the accompanying drawings, which form part of this specification andin which like reference characters refer to like parts throughout theseveral views, Figure 1 is a' vertical cross-section of an ovenembodying my invention, the section being taken on the line 11 of Fig.2; Fig. 2 is a horizontal section on the line 2-2 of Fig. 1; Fig. 3 is adetail in horizontal section showing the ignition plug; Fig. 4 is a rearelevation with parts in section; Fig. 5 is a detail in end elevationwith a part in section taken on the line 55 of Fig. 6, showing the gasand air inlet to a burner; Fig. 6 is a detail in horizontal sectiontaken on the line 6-6 of Fig. showing the gas and air inlet toa burner;

Fig. 7 is a fragmentary top plan of the bottom plate of the heatingchamber of the oven; Fig. 8 is a fragmentary bottom plan of the bottomplate of the heating chamber of the oven; Fig. 9 is a fragmentaryvertical section taken on the line 99 of Fig. 7; Fig. 10 is an enlargeddetail in vertical section in end elevation, showin a large or propershowing the cam wheel and its associated' showing the safety device ofthe ignition mechanism; Fig. 13 is a fragmentary detail thesame parts asare shown in Fig, 12; Fig. 14 is a detail in horizontal section, showingtheasame parts as are shown in Fig. .12, ,the section being taken on theline 1 1-14 of Fig. 13;

In the form of construction which I have shown as embodying myinvention, the oven as a whole is supported upon legs 1 and comprisesanouter chamber 2 provided with double walls 3 and 4. Between the walls3 and. 4 is packed a material 5 having heat insulating qualities,preferably mineral wool. The front wall of the chamber'2 is providedwith a door opening 6, the faces of the side edges of which incline fromthe inside outwardly. In the door opening ismounted, on any suitableform of hinges 7, a door 8, which is similar in construction to thewalls of the chamber and is formed with double walls 9 and 10 packedwith heat-insulated material 11.- The edge faces of thedoor 8 areinclined to fit tightly against the edge faces of the door opening 6.The door 8 is provided with any suitable form of catch 12.

Within the chamber2 is disposed the heating or cooking chamber 13 of theoven, which comprises a top plate 14, a bottom plate 15, andtwo sideplates 16 and 17. The rear wall of the heating chamber 13 is formed bythe rear inside wall of the chamber 2, and the front wall is formed bythe rear wall of the door 8. The heating chamber 13 is heated by burnerswhich are preferably 'arranged in pairs extending from the front to theback of the chamber 2. The burners are shown in this instance as beingperforated tubes 18, each of which is secured to the front inside wallof the chamber 2 by a flanged socket 19 (Fig. 3). Each of the tubes 18is secured at its rear end by an upstanding bracket 20.

Over the rear end of the burner tubes 18 are caps 21. with rounded rims.Each of the caps 21. is provided with apair of segmental openings 22,and fitted over the end face of each cap 21 is a cover 23 havingsegmental tion on ac'entral boss 25 on each cap 21 and 1 has itscircumferential edges bent in to press pipe 26 is provided with ascrew-threaded.

plug 29 opposite the end of each inlet pipe 27, and these plugs 29 maybe removed to clean the inlet pipes 27. The main pipe 26 issupported bybrackets '30 secured to the outside rear wall of the chamber 2. Thesegmental openings 22 and'24 in the cap 21 and cover 23 when registeredserve to conduct air'to the burner tubes 18. The rear wall of thechamber 2 is provided with a rectangular opening 31 to permit the air tohave access to the burner tubes 18.

The bottom plate 15 of the heating chamber 13 is supported uponangle'irons 32 extending from the rear inside wall of the chamber 2 tothe front inside wall. The

. bottom plate 15 is provided with a number of perforations 33 arrangedin transversely and longitudinally extending rows, the perby transverse.and

forations 33 being in staggered relation toone another. On the top faceof the bottom plate 15' the perforations 33 are connected longitudinalgrooves 34 V-shape in cross-sectlon and intersecting with one another.On the bottom face of the bottom plate 15 are similar grooves 35 whichpass between the perforations 33. The grooves 35. on'the bottom face ofthebottom plate 15 serve to increase the heatmg bottom plate 15 increasethe heating surface and also permit the heated air passing through theperforations 33 to spread'out i into along the bottom ofany cookingvessel standing on the bottom plate. The side-plates 16 and 17 of theheating chamber 13 are supported upon the angle irons 32. Each of the'side-plates 16 and 17 isheldrin position by a pair of angle brackets36riveted or otherwise secured to the rear inside wallof the chamber 2and to the corresponding side-plate. The side-plates 16 and 17. arespaced from the inside side walls of the chamber 2 and are provided witha plurality of projections37 extending the spaces. Theseprojections 37are preferably conical in shape and integral surface of the bottomplate. ,The perforations 33 through the bottom plate 15 serve to conductheated air from the burnerplate 14 rests upon the top edges of the sie-plates 16 and 17 and is held in osition by rivets, or other suitableform of astening' means, passed through integral lugs 38 into the rearinside wall of the cham her 2.

' In the rear wall of the chamberis 9. rectangular vent opening 39having its lower edge approximately level with the top face serves tocarry ofi' the products 0 com ustion from the inside of the chamber 2and prevents. the air within the chamber from becoming too impure forproper combustion of the gas.

Formed integral with the top plate on its top face are a number ofspaced bafiie plates 40 extending angularly toward the front of the topplate 14. These baflle plates 40 extendto the top of the chamber 2 andserve to distribute the heated air passing up through the. side spacesevenly over'the top face of the top plate 14. In each of the side-plates16 and 17 .at the top and bottom near the front edge are small holes 41.The top plate 14 is rovided with a number of projections 14' mtegraltherewith and arranged in staggered relation to one another intransverse and longitudinal rows.

The bottom plate 15, side-plates 16 and 17, and top plate 14 arecomposed of some heat-absorbing material, preferably cast iron. Disposedwithin the heating chamber 13 are a number of slidable shelves 42supported on angle irons 43 suitably fastened to the side-plates 16 and17.

The main supply pipe 26 is provided with a valve 44 of the rotary type.The valve stem of the valve is connected to a shaft 45 which issupported in a bracket 46 at one end, and in a pair of spaced brackets47at the other end. Encircling the shaft 45 is a coiled spring 48, theends of which are secured to the shaft 45 and to the bracket 46respectively. The spring 48 is wound so as to bend to turn the shaft 45in the direction indicated by the arrow on Figs. 1 and 11, and to. turnthe valve 44 to its closed position.

The vent opening 39 is provided with a sliding damper 49 fastened to oneend of a sliding damper rod' 50, which is supported in gui es 51. Theother end of the sliding damper rod 50 has fastened thereto a slidingdamper 52 which is adapted to cover the inlet opening 31. This slidingdamper v52 is provided'with slots 53 to pass over the of the top plate14. This vent o own 39 I connected" a link 56.

inlet pipes 27, and secured to the outside wall of the chamber 2 belowthe inlet pipes are strips 54 which underlie the slots 53 when thedamper 52 is in its closed position.

Secured to the end of the shaft 45, which is extended beyond the valve44, is a crank arm 55, and to this crank arm is pivotally This link 56extends across the back wall of the chamber 2 and is pivotally connectedto the'ends of a link 57 and a link 58. The link 57 is pivotallyconnected at its other end to the damper 49. The link 58 is pivotallyconnected at its other end to the outside-wall of the chamber 2. Thesliding damper rod 50 is provided with an angularly extended perforatedlug 59, in the perforation of which is the bent end of a piston 10d 60.Attached to the piston rod 60 is a piston 61 which fitsinto an air-tightdash-pot cylinder 62. The dashpot cylinder 62 is provided at its lowerend with an adjustable relief valve 63.

The damper 49 is provided with a small perforation 64. In the closedposition of the damper 49 the perforation 64 may be coveredby anauxiliary damper plate 65.

mounted on the end of a slidable rod 66. The slidable rod 66 is mountedat one end in a guide 67 secured to the top of the chamber 2 and itsother end passes through alined openings in the inner and outer Walls ofthefront of the chamber.

A knob 68 fastened to the end of the rod 66 which extends through thefront walls of the chamber 2 furnishes a convenient means formanipulating the rod.

A hood 69 is pl ced over the damper 49 and the vent opening 39 and issecured to the rear outside wall of the chamber 2 by rivets passingthrough marginal flanges of the hood. The hood 69 is formed with a slot7 0 to accommodate the movement of the link 57 and the sliding damperrod 50. The walls ofthe hood 69converge at the top to form a pipe '71,which is adapted to have secured to it any desired length of pipe (notshown) leading to the outside air.

The spring 48 tends to turn theshaft 45 to a position to close thedampers 49 and 52 and the valve 44. A device is provided which holds theshaft 45 against the action of the spring 48 in the posit-ion'where thedampers 49 and 52 and the valve 44 are open, and which is operated torelease the shaft 45 when the heating chamber has attained a certainpredetermined temperature. Disposed within the spaces between thesideplates 16 and 17 and the inside walls of the chamber 2 near thefront is a pair of rods 72 and 73. These rods 72 and 73 are com-'posedof a material capable of expanding when heated and are preferablycopper Between each side-plate 16 and 17 and the her 2'by a bolt 74*.

corresponding side Wall of the chamber 2 is fastened a bar 74 Z-shape incross section, which is located near the front of the chamber 2, back ofthe rods 72 and 73, and which is extended from the top to the bottom ofthe side-plate. These bars 74 serve to protect the rods 72 and 73 fromthe direct act1on of the heat of the burner tubes 18, and make itcertain that the parts of the heatmg chamber 13 will be evenly heated tothe same temperature as the rods. I have found that it is desirable in'some instances to cover the rods 72 and73 with a thin layer of asbestosor some other poor conductor of heat in order to secure the sametemperature of the rods and of the parts of the heating chamber 13.

One of the rods 72 is fastened at its upper end to the inside front wallof the chain? The lower end of this rod 72 is pivotally connected to thebifurcated end of a lever 75 by a pin 76. The lever 7 5 is pivoted on abolt 77 secured to the inside front wall of the chamber 2 at a pointlocated at a distance approximately one-fourth of the length of thelever from the bifurcated end thereof to which the lower end of the rod72 is pivoted. The other end of the lever 75 is bifurcated and ispivoted by a pin'78to the lower end of the other rod 73. The upper endof this rod 73 I extends through a circular hole in the top of thechamber and is pivoted by a pin 79 to the bifurcated end of a bar 80.The bar 80 extends across the top of the chamber 2 on the outside nearthe front and one end projects beyond the side of the chamber. Thisprojecting end is bifurcated and is pivoted by a pin 81 to the upper endof a rod 82. The rod 82 extends down the side of the chamber 2 on theoutside near the front and is guided between its ends in a bracket 83.

Below the bracket 83 the rod is curved out wardly, then downwardlyandvits lower end The end of this hook portion 84 is formed with anupward incline 85 and at the end of this incline is pivoted a roller 86.

Fixed to the shaft 45 between the brackets 47 is a sleeve 87 having aradially extending finger 88. 'Thefinger 88 is shaped at its end toforma laterally extending projection 89 curved on the arcof circle. Theprojection 89 is adapted to engage with the roller 86.

Pivotally mounted in a slot in the circumferential face of the sleeve 7is a rolle 96 which is adapted to bear against the lower downwardlyextending portion of the rod 82.

Fixed to the end of the shaft 45 by a pin 91 is an arm 92 provided with:1, vxmnlea handle 93. I

Fastened to the top of the chamber 2 on the outside at a pointapproximately onethird of the length of the bar 80from the ivoted, 95 isend thereof to which the rod 82 is is a U-shaped bracket 94. Ashamounted 'for rotation in the arms of the of the bracket 94 is a leafspring 97 which presses against the side of the cam wheel 96 and by thefriction of its. contact holds the cam wheel in its different positions.A

housing 98 is positioned over the bar 80, bracket 94 and cam wheel 96.The housing 98 is provided with a. slot 99 extending downwardly from theshaft 95 to the bottom so that the housing 98 may be removed to giveaccess to the difl'erent parts. A dial 100 is secured to the bracket 94and is dis posed on the outside of the housing 98. inned to the shaft'95 is a knob 101 carrying a pointer 102 which is arrangedto moveoverthe face of the dial 100. The dial 100 is preferably graduated in spacesto represent degrees of temperature. Bearing upwardlyagainst the barSOnear the end to which the rod 82 is pivoted, is a leaf spring 103fastened to the chamber 2. Above the bar 80 at this point is a tapbolt'104.which is screw-threaded into the housing 98 and bears againstthe top of the bar 80.

Forthe purpose of lighting'the gas burners with the least amount ofdifiiculty there is provided a mechanism for igniting the gas burners byan electric spark. Near the front, through one of the side walls of& thechamber 2, is a tube 105 which is flanged at H one end and fastened byscrews to the outher 2 be open when the side wall of the chamber 2. Theother end of the tube 105 extends within the chamber 2 to a point aboveand to one side of one of the burner tubes 18 and this point ispreferably outside of the path of the flame When the adjacent burnertube is lighted. The bore of the tube 105 is filled with insulation 106in which is embedded a rod 107. The rod 107 extends beyond the inner endof the tube 105 and is bent to bring its tip end adjacent to the endface of the tube. The

tube 105 and the rod 107 constitute a simple construction for formingand positioning an electric spark.

It is desirable that the door 8 of the chamgas is ignited so that therewill not be any damage done in case there is some explosive force to theignition. A rectangular plate 108 is fastened by screws to the outsidefront wall of the chamber EZ'near the edge of the door 8. An angle lever109 is pivotally mounted on the plate 108 by a screw 110, and one end111 of the I angle lever 109 engages a block 112 screwed to the outsideface of the door 8 near its hinged edge.

Supportedbetween a lug 113 on the plate 108 and the end 111- of theangle lever 109 is an expanding coil spring 114 which serves to projectthe end of the angle lever when the door 8 is in open'position. Theother end of the angle lever 109 is bent back to extend parallel withtheside of, the chamber and terminates in a spring contact member 115.The arm 92 has a contact tongue 116.

member 115 is raised out of alinementwith the contact tongue 116. Asuitable housing 118 .is placed over the angle lever 109 and spring 114.r

The circuits of the electrical igniting mechanism are showndiagrammatically in Fig. 2. Any suitable form of battery 119 andinduction or spark coil .120 may be used. The circuit for the primary ofthe induction coil is as follows: positive of the battery 119, conductor121, primary of the coil 120, conductor 122, contact member 117,contact.

tongue 116, contact member 115, to thebody of the chamber 2, andconductor 123 back to the negative of the battery 119. The circuit forthe secondary of the induction coil is as follows: From one terminal ofthe secondary by conductor 124 to rod 107, air ap between the rod 107and the tube 105 tu e 105, body of chamber 2, conductor 123, conductor125, back to the otherterminal of the secondary.

In the operation of the device shown and described, the door 8 is firstopened. The door 8 being in open position, the end 111 of the anglelever 109 is permitted to pro- I ject under the force of the spring 114,and

the contact member 115 is positioned opposite the contact member 117.The handle 93 is now turned to the left (accordin to Fig. 11). Thismovement, by rocking t e shaft '45, opens the valve 44 and the contacttongue 116 by engaging between the con-' tact member 115 and the contactmember 117, completes the circuit through the primary of the inductioncoil 120. The secondary of the induction coil 120 causes a spark acrossthe air gap between the rod 107 and the tube 105, and this spark ignitesthe gas.

incline 8 5 and pushes'down the horizontal lever 109 is forced back andthe" contact During the movement of the handle 93 to the left, the arm88 engages the 1,135,700 fijli.

portion 84 of the rod 82. After the gas is ignited, the handle 93 isreleased and the spring 48 rocks the shaft 45 to the position shown I inFigs. 2 and 14. In this position the roller 86 engages the roundedprojection 89 of the arm 88 and holds the shaft 45 against returnmovement, the contact tongue 116 being out of engagement with thecontact members 115 and 117. In this position of the shaft 45 the valve44 and the dampers 49 and 52 are in full open position. lVhen it is seenthat the gas is lighted, the door 8 is closed. The cam wheel 96 is nowadjusted by the knob 101 to place the pointer 102 opposite the mark onthe dial 100 which corresponds to the temperature at which it is desiredto shut off the supply of gas. The manipulation of the device is nowended and further operation is automatic.

As the heating chamber 13 becomes heated, the rods 72 and 73 expand andlengthen. On account of the location of the pivot bolt I 77 of thelever'75, the distance which the rod 72 expands is multipliedapproximately four times at the lower end of the rod 73. To

four times the distance which the rod 72 ex-' ands is added the distancewhich the rod 3 expands. The expansion of the rods 72 with the mm wheel96 now becomes a fulcrum for the bar 80 and further upward movement atthe end of the bar 80 to which the rod 73 is. attached causes a downwardmovement of the rod 82. This downward movement of the'rod 82 releasesthe arm 88, permits the spring 48 to rock the shaft 45, carrying with itthe crank arm 55. movement of the crank arm 55 by means of the links 56,57 and 58 pulls the sliding damper rod 50 downward to close the dampers49 and 52. The dash-pot cylinder 62 prevents too rapid and sudden amovement of the sliding damper rod 50. The tap belt 104 is adjusted sothat the upper position of the rod 82 places the axis of the roller 86nearer the center of the shaft 45 than the point of contact of theroller 86 and the rounded end of the projection 89 of the arm 88. Theparts may be adjusted so that the shaft 45 will be held against movementin the direction of the arrow on Figs. 1 and 11, and yet will bereleased by a very small movement of the rod 82.

The air supplied to the burner tubes 18 is regulated by turning thecovers 23, and the gas may be regulated by substituting for the plugs 28other plugs having different sized bores. The holes 41 in theside-plates 16 and 17 allow steam and vapor in the heating chamber 13 topass out into the chamber 2. When the damper 49 is opened, this steam orvapor may pass with the heated air out through the vent opening 39. Whenthe The and vapor in the heating chamber 13 may be permitted to escapewhile the heating chamher is closed.

An oven constructed according to my invention will use much less gasthan an oven of the ordinary type. In the ordinary oven, a largeproportion of the heat passes through the side walls into thesurrounding room. This makes the temperature in the room uncomfortablyhigh and also Wastes heat.

It can be determined accurately what temperature of the heating chamberis necessary to properly cook different kinds of food, and when thepointer is set to that temperature on the dial, no further attention isnecessary. Also, it is certain that the food will not be overcooked orspoiled by being burned. It has been found by actual tests that a singlemeal may be cooked in an oven of the type shown and described with onlyone-half of the gas needed to cook the same meal in an oven of theordinary type. In these tests, a

cold oven was used, and ifv it can be arranged to take advantage of anoven partly heated from a preceding cooking operation, much greatereconomy can be effected.

Obviously, the oven which I have shown and described as an embodiment ofmy invention may be considerably modified without departing from thespirit of my invention. Therefore, I do not wish to be limited to theparticular construction illustrated and described.

What I claim is:

1. In an oven, a chamber having double walls filled with a heatinsulating material, a cooking chamber in said chamber having metalWalls spaced from the inner walls of said chamber, said first mentionedchamber completely surrounding said cooking chamber, a burner below saidcooking chamber and heating the bottom, top and side walls thereof, avalve for controlling the supply of heating medium to said burner, avent opening in said first mentioned chamber, a damper for closing saidvent opening, a member mounted in said chamber and capable of expandingwhen heated, means controlled by said member for closing said valve andsaid damper, and means for varying the amount of movement of said membernecessary to set said last mentioned means into operation.

2. In an oven, a chamber having double walls filled with a heatinsulating material, a cooking chamber withinsaid chamber and havingmetal top, bottom and two side walls spaced from the inner walls of saidchamber, said side walls and said top of said cooking arranged instaggered relation, said pins extending out into the space betweenthetop and two side walls of said cooking chamber and the inner walls ofsaid first mentioned chamber, a vent opening in said first menthereofand above the top of said cooking chamber, and a plurality ofbaflleplates on the upper surface ofthe top of said cooking chamber,said bafile plates extending at an angle to said walls of said cookingchamber.

3. In an oven, a chamber, a burner within said chamber,acooln'ngchamberjvitliinsaid top -face,"o

transverse and longitudmal grooves-interchamber having its top, bottomtwo side walls spaced iromthe inner walls-of 15 said chamber, saidbottom being disposed above'said burnerand comprising a metal platehaving a series of holes therein arranged in transverse and longitudinalrows and in stag cred relation to one an'other,.the

' said. plate being formed with secting .said holes, and the bottom faceof said plate being formed with transverse and longitudinal grooveslying between sald 2 ho1es and intersecting one. another.

4. In an oven, a chamber, a cooking chamberwithin-said chamber andhaving its top, 1 bottom and two side walls spaced from the inner wallsof said chamber, said top, and

tween the inner walls of said chamber and 5 tioned chamber located inthe rear wall 3!) side walls being ofamaterial capable of absorbing heatand having on their faces aplurality of integral pins arranged instaggered relation and extending out into the space besaid top, and twoside walls, the under facefor supplying air to of the bottom of saidcooking chamber hav ing a number of intersecting grooves therein.

5. In an oven, a chamber having walls of a material capable of absorbingheat, heat -40 insulated walls completely surrounding said chamber,there being a space between the top, bottom and walls of said cookingchamber and said heat insulated walls, a gas burner for heating saidchamber, an opening said' burner, a vent openmg, dampers for closin saidopening and said vent opening, a va ve controlling the supply of gas tosaid burner, means for closing said valve and for "shutting said .velvfor 'cpntr l g t rounding said (member,

valve o en, said'means being opersted by;

va ve,an means" said member to release said for varying the amount ofmovement of said member necessary to set said last mentioned means intooperation.

7. an oven, a cookingchamber," heat in-- sulated .walls surrounding saidchamber, a burner for supplying heat'to said chamber, a

mediumto ;said burner-,a aft operatively connected to. valve, 8. springconnected sulpply of heating to said shaft and ten g to turn said shaftin the direction to close said valve, avent opening the heat insulatedwalls sura damper for closing ud -Y. open ng shaft,"a,t ripme'c anismfor holding said shaft in the pqsiti (n in which said valve and andconnected to said said damper'are open, and means controlled i by thetem erature in said chamber torlre leasing said tri mechanism, saidmeans being adjustable cm the outsideof'said heat insulatedwalls,-whereby the temperature at which said.- Yalve'and said damperswill be closed can bevaried."

8. In an oven, :1 cooking chamber, heat insulated' walls1 surroundingsaid chamber, a

burner for supplying heat to said chamber, a valve forgcontrolling thesupply of. heating medium to said burner, a vent opening in the,heat'-;.insu'lated walls surroundin said chamber, a damper for closingsai vent opening, means. tending to close said damper, and a dash-potfor retarding the closing movement of said damper, the closing movementof said damper being controlled by the closing movement of said valve.

9. In-- an oven, a cooking chamber having walls of a material capable ofabsorbing -rounding said chamber,

' f .50, dampers, said means be controlled by temperature in said chamer, said mean's'being adjustable "whereby the amount ofheat supplied tosaid cooking chamber necessary to set said means into operation can be.515; varied.

a 6. In an oven, :1. cooking chamber,said cooking chamber beingcompletely surrounded by a second chamberhaving heat insulated walls, agas burner within said #0.. second chamber for heating said cookingchamber, a valve for controllin of gas to said burner, a spring ornormally closing said valve, a member mounted in said secgxlid chamberand cafpableof expandthe supply heated, means or holding said heat, heatinsulated walls completely surthere being a space between said cookingchamber and said .heat

insulated walls, a-"gas burner for supplying heat to said chamber,avalve for controlling the supply of gas to said burner, a vent opening.in said chamber, a damper for closing said vent opening, and means fordamper,-said means being controlled by the temperature in said chamber,said means shutting said valve and for closing said being..adjustablefrom the outside of said heat insulated walls, whereby the amount ofheat supplied tos'aid'cooln'ng chamber which .is necessary to set saidmeans into ope'ration a heat insulated chamber,

the supplyof gas to said burner.

tric device 'forlighting said. burner which.

a gas burner for supplying heat to said chamber, mechanism forautomatically cutting off the supply of gas to said burner after apredetermined amount of heat has been supplied to "said chamber, meansfor lighting said burner which is set into operation when said mechanismis placed in operative position, and a door in said chamber, said meansfor lighting said burner being incapable of being operated when saiddoor is closed.

12. In an oven, a heat insulating chamber, a gas burner for supplyingheat to said chamber, a valve for controlling the supply of gas to saidburner, a rotatable shaftconnected to said valve for opening and closingit, a bar, members in said chamber capable of expanding when heated andconnee to said bar at one end thereof, a spring connected with saidshaft and tending to move said shaft in a direction to close said valve,trip mechanism for holding said shaft in the position in which saidvalve is open, means operatively connecting said trip mechanism and theother endof said bar, and adjustable means for engaging said'barintermediate the ends thereof and forming a fulcrum for said bar.

13. In an oven, a chamber, a gas burner for supplying heat to saidchamber, a valve for controlling the supply of gas to said blu'ner,

a shaft operatively connected to said valve,

a spring connected to said shaft and tend- I ing to turn said shaft in adirection to close said valve, an arm on said shaft having a rounded endand having a roller rotatably mounted in its side face, a rod having ahook end, the point of said hook end having a roller rotatably mountedtherein, said hook end in its operative positionengaging said arm, theroller on the point of said hook engaging said rounded end of said armwith the axis of the roller nearer the center of the shaft than the lineof contact between said roller and said rounded end, and means formoving said hook out of engagement of said arm to release said shaft.

14. In an oven, a chamber, a door in said chamber, a burner for heatingsaid chamber, a valve for controlling the supply of heating medium tosaid burner, a spring for closing said valve, means for holding saidvalve open, a hand lever for setting said means in operative position,and ignition means set into operation by moving said hand lever to saidoperative position, said ignition means being inoperative when said dooris closed.

15. In an oven, a heat insulated chamber,

"a burner for heatingsaid chamber, a valve forcontrolling the supply ofheating medium tosaid burner, a vent opening for said chamber, an'airopening for supplying airto said burner, dampers for said vent openingand for said air opening, a spring for automatically closing said damperand shutting said valve simultaneously, and a dash pot for retarding themovement of said damper.

16. In an oven, a burner for supplying heat to said oven, a valve forcontrolling the supply of heating medium to said burner, a spring forclosing said valve, trip mechanism holding said valve in its openposition, members within said chamber capable of expanding when heated,a bar connected at one end to. said members and at the other end to saidtrip mechanism, a cam wheel rotatably mounted on said chamber at a pointintermediate the ends of said bar and adapted to be engaged by said barto form a fulcrum therefor, a fixed dial, and a pointer secured to saidcam wheel and movable over the face of said dial.

17. In an oven, a heat insulated chamber, means for heating saidchamber, a vent opening for said chamber, a damper for closing said ventopening and having a small perforation therein, an auxiliary damper foropening and closing said per-' foration when said damper is in closedposition, means for automatically closing said damper when said chamberhas attained a predetermined temperature, said means operating withoutinterfering with said auxiliary damper, and a rod extending through awall of said chamber and connected to said auxiliary damper.

18. In an oven, a chamber, a gas burner for heating said chamber, anelectrical igniting device for lighting said burner, a circuit for saidelectrical igniting device, a valve for controlling the supply of gas tosaid burner, a hand lever connected to said valve and having a contacttongue for closing said circuit, a spring operatively connected to saidhand lever and tending to close said valve, and releasable means forholding said hand lever in the position where said valve is open andsaid circuit is broken.

19. In an oven, a chamber, a gas burner for heating said chamber, avalve for controlling the supply of gas to said burner, a springconnected to said valve and tending to close it, a trip device. forholding said valve open, a member in said chamber capable of expandingwhen heated, means operatively connecting said member and said tripdevice, and a means for varying the amount of movement of said membernecessary to set

